Power control



May 12, 1942 l M. .1. KITTLER ET AL 2,283,005

POWER CONTROL Filed Aug. 17, 195s Q57 l @1795, .cnw

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.S Tfr/v1 n f7. dof/Af ATTORNEY A Patented May 12, `1942 POWER CONTROLMilton J. xmmana stanley M. Udale, Detroit, Mich., assignors to GeorgeM. Holley and Earl Holley 'Application August misas, serial No. 225,392

4 claims. (ci. 12a-103) 'I'he object of this invention is to maintainthe power of a supercharger engine substantially constant as thealtitude increases.

In the drawing: Figure l shows the preferred form of our in- Figure 2shows a cross sectional elevation on plane 2-2 of Figure 1.

In the gures, I is a well known type of vacuum pump. The vacuumconnection leads to a stationary tube |I which is mounted on a supportI2. This stationary tube I| has a solid end in which there is a grooveI3, this groove I3 serving to locate an oscillating cylinder |4 by meansof a set screw I5. The tube II thus acts as a Apivot for supporting theoscillating cylinder I4.

Inside the oscillating .cylinder I4 is a sliding piston I5 connected toa piston rod I8 which carries the throttle ball-connection I1. 'Ihepiston I5 is supported by a spring I8 which is supported by a springholder I9 which rides on a rod 20 which carries a roller 2| whichengages with a cam surface 22. The vacuum from the vacuum pump I0 isadmitted to the under side of the piston I5 through a passage 28.

'I'he carburetor as such is not shown. It is merely indicated by thethrottle valve 24 which is operated by a lever 25 connected by a link 28with the ball-connection I'I. 'Ihe throttle valve 24 admits mixture tothe supercharger 21 which supplies compressed charge through the pipe 28to the upper side of the piston I5. 'I'he pipe 28 twists in theoscillating cylinder |4 and is held in place by a bushing 28 and by aspring 30.

The hand control lever 3| is integral with the oscillating cylinder I4and is so arranged that as the oscillating lever 3l moves 45 to the leftin Figure 1, the path of the ball end I1 is at right angles to the link26, so that when the throttle lever 3| is in the idle position it doesnot make any dierence what the atmospheric pressure is or what thepressure n the supercharger is, as the valve 24 will be in the closedposition in any case.

charger 21 will create a pressure in the engine cylinders which will bebeyond the strength of the engine. In order to protect the engine fromthe excessive power which is produced under the abnormal circumstancesof ying' close to the earth, it is necessary to reduce this power sothat vwhen the plane reaches the normal altitude, two

or three miles in the air, the engine can then develop its maximumpower.

The vacuum pump ID creates a vacuum which acts on the under side of thepiston I5 and compresses the spring I8. On the top of the piston I5 thepressure is applied through the pipe 28 corresponding to the pressurecreated by the supercharger 21. The ball joint I'I is moved towards thecenter around which the throttle lever 8| rotates. Hence the effectivestroke'of the throttle lever is reduced. If the throttle lever is in theidling position, approximately 45, the motion of the ball joint I1 awayfrom and towards the center of rotation does not influence lthe idlingposition of the throttle 24. However, as the throttle lever 3| is movedto the wide open position, .the corresponding position of` the throttle24 is determined by the pressure of the supercharger.

The characteristic of all compression springs is that as they arecompressed, their resistance It is only when the throttle lever 8| ismoved Operation Assume that the plane isv taking o at an airport withina few thousand feet of sea level. When the throttle 24 is'opened wide,the superincreases arithmetically with the degree oi compression. Hence,when ilying under normal conditions, two or three miles in the air, theball joint I1 rises'and the spring I8 expands and a lower pressure isneeded to balance the spring pressure against the supercharger pressure.Therefore, as the plane ascends to normal altitudes, the superchargerpressure decreases. This decrease in the supercharger pressure isnecessarybecause if the spring I8 were replaced by a weight and pulleyso that the same supercharger pressure is maintained at normal altitudesas at sea level, there would be a large increase of power at altitudedue to the fact that the back pressure would diminish and therefore,there would be a greater filling of the cylinder, a greater quantity ofmixture would enter the engine,l and therefore, a greater amount ofpower would be developed at normal altitudes than at sea level. l

Obviously it is desirable that an engine develop the same power at sealevel as at normal altitudes, and if there is any deviation it should besuch that maximum power is developed at sea level for obvious reasons.In other words, the desirable engine specification calls for eitherconstant power or one or two percent loss of II be reduced so that theengine automatically maintains a lower supercharger pressure than itmaintains at wide open throttle. The roller 2| (Fig. l) follows the camu. Hence the spring abutment Il descends in the cylinder Il when thethrottle lever is rotated counter-clockwise, and

reduces the pressure on the spring Il and therefore, the devicemaintains a lower pressure when the throttle lever lis in half openposition than when in wide open position.

What we claim is:

1. In a manually operated throttle control for a supercharger airplaneengine, means for obtaining a continuous vacuum, an oscillatingcylinder, a piston therein, means for applying the vacuum to theunderside of the piston, means for applying the supercharger pressure to`the upper side of the piston, a piston rod connected to said piston, athrottle connection located on said piston rod, a compression springengaging with said piston so as to balance the absolute pressure of saidsupercharger pressure, means for 80 oscillating said cylinder, saidcylinder being so mounted that when the throttle is in the closedposition, the movement of the piston in response to superchargerpressure does not move the throttle, and when the oscillating cylinderis moved into the position to open the throttle, the degree of openingthe throttle is determined by theabsolute pressure in the superchargerso that any excess of supercharger pressure causes the throttle to closeslightly.

2. In a device as set forth in claim 1 in which means are provided forincreasing the compression of the spring as the throttle lever is movedfrom the closed position into the open position.

3. In combination with a manually operated throttle control for asupercharged engine, control means comprising a manually operatedmember, a link having an adjustable connection therefor, a pistonconnected to both the manually operated member and to the link, a springadapted to move the piston so as to' completely open the throttle whenthe manually operated member is in its wide open position, meansdirectlyresponsive to the absolute' pressure developed by the superchargeracting on the piston to increase the strain on the spring so that at sealevel the supercharger pressure is higher when the piston is inequilibrium and the throttle is partly closed, than at altitude when thethrottle is wide open and the piston isin equilibrium at a lowersupercharged pressure with a partially released spring, the means forpositioning the piston being a spring which opposes the of the pressurein the supercharger, -a'nd means whereby the strength of thisopposition' increases as the manually operated throttle controlyis movedfrom the idle position into the. ,open throttle position.

4. In a supercharged airplane engine a vacuum pump, a manually operatedthrottle control lever' f v having a variable length, piston andcylinder means incorporated in said throttle control lever, a passageconnecting one end of the cylinder with the vacuum pump, a passageconnecting the other end of the cylinder with the supercharged pressure,spring means for balancing the piston, said spring means being adaptedto balance the piston when the throttle is partly closed at a highersupercharged pressure when at sea level than at altitude when thethrottle is wide open and the strain on the spring is partiallyreleased.

MILTON J. KI'I'I'LER. STANLEY M. UDALE.

